The invention relates to a device for regulating the temperature of the intake air of a mixture-compressing internal combustion engine with a pressure box, wherein a moving part extends into the pressure box.
Sealing systems are known in which synthetic resin or rubber rings are placed in the pressure box and surround the moving part in a pressure-tight manner. Also, it is considered to be known to guide a moving part in synthetic resin friction bearings.
In DE 26 24 210 C2 a device of this general kind is disclosed in which, in order to regulate the temperature of the intake air of mixture-compressing internal combustion engines, a control flap in the raw air connection of an intake air filter cooperates with a pneumatic adjusting motor, or pressure box. In one end position, by means of a return spring passing through a pressure control chamber, a warm air passage is closed if the pressure falls below a predetermined target vacuum and at the same time a cold air passage is opened, the pressure control chamber of the servo motor being connected through a pressure control line to the section of the air intake duct situated downstream from an arbitrarily operated main throttle valve. The pressure control line has a valve which is actuated in dependence on the temperature and which contains a valve body operated by a bimetal strip, and moves the valve body to the open position when the predetermined target temperature is reached in order to open a connection to the clean air chamber of the intake air filter.
Such a device serves to keep the temperature of the intake air of the internal combustion engine within a certain range. Only when the main throttle valve is opened, i.e., under full-load operating conditions, is the internal combustion engine to draw in colder air so as to achieve a better degree of fill and a higher power.
The guidance of the operating rod from the pressure box adjusting motor to the pivotable control flap is in this case problematical, since not only can forces arise in the direction of thrust, but also lateral deflections must be absorbed.
It is the object of the invention to improve a device of the kind described above such that proper guidance and mechanical movement of the mechanical part extending into the pressure box will be assured, combined with good sealing of the part.
The device of the general kind according to the invention advantageously permits, by a combination of the features as described and claimed herein, after a simple construction of the control of a pivoting flap valve by a pressure box in the intake duct, wherein, in the opening in the pressure box through which a moving mechanical part can be extended into the interior of the pressure box, a good seal is achieved and at the same time the movement and guidance of the mechanical part is assured.
In accordance with the invention, an operating rod is formed as a mechanical part from elements which can turn about an additional axis. The entire sealing and guiding system is advantageously formed from a synthetic resin friction bearing in contact over a given length with the moving element of the mechanical part which bearing is firmly anchored over the entire sealing system, including in the opening in the pressure box, and at one end of the synthetic resin friction bearing a Teflon ring is arranged in the sealing system which surrounds the moving part in a pressure-tight manner.
In one advantageous embodiment, a ring of elastomer is disposed externally around the Teflon ring in the sealing system, and tightly grips the Teflon ring. Such combinations of a sealing ring and an element encompassing the sealing ring are themselves known in normal piston guiding means, for example from U.S. Pat. No. 4,878,766. According to the invention, however, the peculiarities in the case of pressure boxes, with regard to the specific combination of the action of the seal and the unavoidable lateral deflection of the operating rod and the specific guidance problems which thus arise, play an important role. Simple installation of the device in an air induction system for an internal combustion engine is achievable if the vacuum box can be integrated by a bayonet lock into the raw air intake nipple.
In the previously described embodiment, the vacuum box advantageously performs guiding functions for the linkage, as mentioned, so that here a separate bearing in the air intake housing is unnecessary. Due to the sealed linkage, sealed especially against the intake duct vacuum, it is possible to mount the vacuum box simply and directly into an intake duct housing.
These and additional features of preferred embodiments of the invention will be found not only in the claims but also in the description and the drawings, the individual features being applicable individually or jointly in the form of subcombinations in embodiments of the invention and in other fields and may represent advantageous as well as independently patentable embodiments, for which protection is hereby claimed.